Electronic sewing machine

ABSTRACT

A plurality of different stitch patterns are stored in a first static memory. A second static memory memorizes a combination of these different patterns in a predetermined sequence. A third static memory stores basic needle position signals each specific to the patterns stored in the first memory. Calculating means utilize signals derived from the second memory and the third memory to determine values for adjusting the swinging amplitude of the sewing needle with a common variation rate and for setting a common basic needle position.

BACKGROUND OF THE INVENTION

The invention relates to a sewing machine electronically storing the stitch control data which are sequentially read out to produce various patterns of stitches. More particularly the objective of the invention is to control the basic or reference needle position of a member of patterns which are produced sequentially in combination by such a type of sewing machine.

In a zigzag sewing machine which may produce various patterns, it is generally required to produce the stitch patterns with a predetermined basic (or reference) needle position which may be located at the right end, left end or the middle of the maximum swinging range of the needle most properly for the patterns. In case the sewing machine operator wishes to produce a number of patterns sequentially in combination especially with adjustment of the needle swinging amplitude, it is undesirable that the needle swinging amplitude be adjusted on both sides of the basic needle positions which may be different in dependence upon the different patterns. Namely, it is undesirable to shift the basic needle positions each in dependence upon the different patterns. It is therefore a primary object of the invention to memorize a combination of different patterns with designation of a basic (or reference) needle position common to these patterns.

According to the conventional sewing machine producing stitch patterns including straight stitches, the straight stitches are produced with a basic needle position generally set at the center (or middle) M of the maximum swinging range of the needle. It is actually desirable for many stitch patterns including zigzag stitches to set the basic needle position at the center M of the maximum needle swinging range. This requirement, however, different with respect to a pattern such as a pattern of a tulip as shown in FIGS. 1(A) and 1(B). As to the patterns such as the tulip, it is preferable to set the basic needle position at the left end L of the maximum needle swinging range, because such a pattern is easily positioned with the basic needle position L with respect to the fabric to be sewn, and because the pattern may be varied in size from minimum to maximum with reference to the basic needle position L. As to the pattern of blind stitches, it is preferable to set the basic needle position at the left end L of the maximum needle swinging range, because such stitches are produced with reference to the edge of the fabric to be sewn. No problem arises if the different stitch patterns of different basic needle positions are produced separately and individually. A problem arises if these patterns are produced sequentially in combination. Namely, the difference of basic needle positions prevents the combination of patterns from being produced in alignment with each other. Actually if the combined patterns of different basic needle positions are produced in the maximum size in the maximun needle swinging range, these patterns are produced in alignment with each other and no problem arises as shown in FIG. 1(A). On the other hand, if the size of these combined patterns are adjusted (or reduced), these patterns are so reduced with reference to the difference basic needle positions each specific to the patterns, and as the result, the sequential patterns are produced to and fro out of alignment.

SUMMARY OF THE INVENTION

An object of the present invention is to solve such a problem of the prior art. In keeping with this object and other which will become apparent hereafter, the invention substantially comprises; a first memory storing stitch control data for different stitch patterns to be selectively produced, pattern selecting means including a number of pattern selecting switches which are selectively operated to produce a pattern signal designating the corresponding are of the patterns stored in the first memory, pattern memory control means operated to determine a combination of different patterns, a second memory operated in response to the operation of the pattern selecting means and of the pattern memory control means to memorize the combination of different patterns in a predetermined sequence, needle swing adjusting means operated to adjust the swinging amplitude of the needle with a common variation rate with respect to each of the stitch control data read out from the first memory in response to the designation of the patttern signals memorized in the second memory, a third memory storing basic needle position designating signals each specific to the patterns stored in the first memory, basic needle position control means operated in response to the operation of the pattern memory control means to memorize a specific one of the basic needle position designating signals to control the stitches of the designated combined patterns with a common basic needle position, calculating means operated in response to the output signal of the basic needle control means, the stitch control signal of the first memory and the output signal of the needle swing adjusting means to adjust the swinging amplitude of the needle with a common variation rate with respect to each of the stitches of the combined patterns, and to set a common basic needle position for the patterns, and stitch forming means operated in response to the output of the calculating means to produce the stitches of the combined patterns. According to another feature of the invention, separate and individual patterns are produced with the basic needle positions each specific to the patterns.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A) and 1(B) show by way of an example the stitch patterns to be produced by the invention;

FIG. 2 shows a control circuit of the invention; and

FIGS. 3 and 4 are the timing diagrams showing the operations of the control circuit in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1(A) shows a combination of patterns, a tulip of stitches and a zigzag of stitches which are stored in a memory to be alternately and repeatedly produced with a full swinging amplitude of needle and with a basic or reference needle position L within the maximum range between the right end needle position R and the left end needle position L corresponding to signals 30 and 0 respectively. The needle position M is the center of the maximum swinging range of the needle and corresponds to a signal 15. FIG. 1(B) shows the same patterns as those of FIG. 1(A), but these patterns are reduced into a half of the patterns of FIG. 1(A) in the zigzag amplitude of needle.

FIG. 2 shows a control circuit designed to produce the patterns as shown in FIG. 1(A) and FIG. 1(B), in which SW₁ is a pattern selecting device including a number of switches selectively operated to produce a pattern signal of a selected pattern to be stitched. An encoder E receives the pattern signal and produces a 3-bit code signal to a latch circuit L₁. Vcc is a positive control power source, and R₁ denotes pull-up resistors. MM₁ is a monostable multivibrator circuit which receives the pattern signal from the pattern selecting device SW₁ through a NAND circuit NAND. The monostable multivibrator circuit has an output terminal Q to give the pattern signal to the trigger terminal of the latch circuit L₁, so that the latch circuit may latch the code signal from the encoder E. RAM is an electronic memory for tempoarily memorize the data of the input terminal IN in the columns designated by a 4-bit address (ad) in accordance to the writing order of a mode designation terminal R/W, and for producing a signal at the output terminal OUT in accordance to a readout order.

ROM₁ is an electronic memory fixedly storing the stitch control data of patterns to be stitched, and has address terminals A₀ -A₁, of which the terminals A₅ -A₇ receive a pattern code signal directly or indirectly from the output terminal OUT of the memory RAM. SW₂ is a memory switch which is operated to produce a falling signal to actuate a monostable multivibrator circuit MM₂. Then the monostable multivibrator circuit MM₂ gives the output at the true side output terminal Q to a delay circuit TD₁ and to one input of AND circuit AND₁ which has another input receiving the complement side output Q. The AND circuit AND₁ has an output connected to one input of NOR circuit NOR₁. R₂ is a pull-up resistor. The NOR circuit NOR₁ has another input receiving the output Q of the monostable multivibrator circuit MM₁, and has an output connected to the mode designation terminal R/W of the memory RAM, so as to memorize or rewrite the signal of latch circuit L₁ into the memory RAM each time the switch SW₁ or SW₂ is operated. When the switches SW₁, SW₂ are not operated, the terminal R/W is high level for ordering the memory RAM to read out the data. When these switches are operated, the terminal R/W temporarily becomes low level for ordering the memory to rewrite the data after a counter CT is operated by operation of the switch SW₂ to advance the addresses of the memory ROM. If the pattern selecting switches SW₁ are selectively operated more than two times without operation of the memory switch SW₂ the last switch is made effective, and accordingly the pattern data is memorized.

The counter CT is reset when the control power source is applied, and has a count-up terminal UP receiving, through OR circuit OR₁, the output of AND circuit AND₂ which receives the true side outputs Q of the monostable multivibrator MM₂ and of the delay circuit TD₁. The counter is operated to count up when the memory switch SW₂ is operated. L₂ is a latch circuit and has an input terminal IN receiving the count-up signal of the counter CT, and has a trigger terminal CP receiving the output signal of the memory switch SW₂ through AND circuit AND₃, OR circuit OR₂ and monostable multivibrator circuit MM₃, said AND circuit AND₃ receiving the complement side output Q of monostable multivibrator circuit MM₂ and the true side output Q of delay circuit TD₁. Thus the latch circuit L₂ latches the count-up signal of the counter CT when the switch SW₂ is operated.

TB is a timing buffer having a reset terminal connected to the output of NOR circuit NOR₁, and produces the output O each time the switches SW₁, SW₂ are operated, and accordingly makes O the address inputs A₀ -A₄ of the memory ROM₁. The timing buffer TB has a trigger terminal CP receiving a pulse signal of a pulse generator PG operated in synchronism with rotation of drive shaft of sewing machine (not shown), thereby to latch the address signals B₀ -B₄ and advance the address of the memory ROM₁ per stitch. The relation between the timing buffer TB and the memory ROM₁ is described in detail in U.S. Pat. No. 4,086,862 and the copending German patent application Ser. No. 26 26 322.9, both of the same applicant.

The memory ROM₁ stores the needle control data DB and the feed control data EF which are to be transmitted to calculating device PVA₁, PVA₂ respectively. The calculating devices PVA₁, PVA₂ receive the adjusting signals of needle swing amplitude adjusting device VRB and of feed adjusting device VRF respectively as the reduction rate data KB, KF through analog-digital converters A/D₁, A/D₂, and make calculations including the multiplications of the data KB, KF and the control data DB, DF respectively to produce the outputs to stitch forming device DV. When the needle control data DB is 0, it designates the needle coordinate R, and when the data is 30, it designates the needle coordinate L. Thus the maximum needle swinging range between 0 and 30 are evenly divided into 30 for so many needle coordinates. When the feed control data DF is 0, it designates the maximum fabric feeding movement in the backward direction, and when the data is 30, it designates the maximum fabric feeding movement in the forward direction.

SW₃ is a controller switch which is closed as a controller (not shown) is operated and produces a falling signal to operate a monostable multivibrator circuit MM₄. R₃ is a pull-up resistor. The monostable multivibrator circuit MM₄ has a true side output Q connected to a set terminal S of JK type flip-flop circuit FF₁ to set the latter when the switch SW₃ is operated. The same circuit MM₄ has a terminal J grounded and of low level, and has a terminal K connected to a true side output terminal Q of the flip-flop circuit FF₁. The flip-flop circuit FF₁ has a trigger terminal CP receiving the output Q of the monostable multivibrator MM₁ and is reset by the falling signal applied thereto. AND circuit AND₄ receives the output Q of the monostable multivibrator circuit MM₄ and the output of delay circuit TD₂ which is operated by the complement side output Q of the flip-flop circuit FF₁. The AND circuit AND₄ has an output connected to the reset terminal R of the counter CT through OR circuit OR₃, so at the reset the counter when the controller switch SW₃ is closed after the pattern selecting switch SW₁ is operated.

The flip-flop circuit FF₁ has the true side output terminal Q connected to a reset terminal R of the monostable multivibrator circuit MM₂ and to the inputs of AND circuits AND₅, AND₆. The address signals A₀ -A₄ of the memory ROM₁ are 0 for the first stitch and operate a monostable multivibrator MM₅ through the NOR circuit NOR₂. The monostable multivibrator MM₅ has an output terminal Q connected to another input of the AND circuit AND₅, which has the output to the count-up terminal UP of the counter CT through the OR circuit OR₁, to start the count-up of the counter CT each time a new pattern is stitched. The AND circuit AND 6 has another input connected to the output Q of the monostable multivibrator MM₁, and is so connected as to reset the counter CT through the OR circuit OR₃ when the pattern selecting switch SW₁ is operated after operation of the controller switch SW₃, and is so connected to latch the value O of the counter CT in the latch circuit L₂, and is so connected to reset a flip-flop circuit FF₂.

Exclusive OR circuits EXOR₁ -EXOR₄ compare the signal of the counter CT and the signal OUT of the latch circuit L₂ as to the bits thereof and, if these bits are all in accord, operate a monostable multivibrator circuit MM₆ through a NOR circuit NOR₃. The output Q of the monostable multivibrator circuit MM₆ resets the counter CT for stitching the first one of the combined patterns.

ROM₂ is an electronic memory fixedly storing the data for controlling the basic (or reference) position of the needle of sewing machine. The memory ROM₂ has the inputs G₀, G₁, G₂ receiving a code signal from the output terminal OUT of the memory RAM, and has an output terminal P for producing an output signal in response to the code signal to control the basic position of needle. The basic needle position control signal is low level directing the basic needle position to the center M for the ordinary stitch patterns including the straight stitches. On the other hand, the basic needle position control signal is high level for the stitch patterns including the tulip patterns as shown in FIG. 1 which require a basic needle position at the left end L of the maximum needle swing range.

The flip-flop circuit FF₂ is, as aforementioned, reset each time the pattern selecting switch SW₁ is operated after operation of the controller switch SW₃, and has a set terminal S receiving the output signal of AND circuit AND₇ which receives the output signal P of the memory ROM₂ and the output of OR circuit OR₁. The pattern designation due to operation of the pattern selecting switch SW₁ maintains the output P of the memory ROM₂ in high level, and the flip-flop circuit FF₂ is set when the memory switch SW₂ is operated. Namely if the patterns memorized in the memory RAM include a pattern or patterns of the basic needle position L, the flip-flop circuit FF₂ is set and the output Q becomes high level. If the memorized patterns include no pattern of the basic needle position L, the output Q remains low level.

NOR circuit NOR₄ receives the output Q of the flip-flop circuit FF₂ and the output P of the memory ROM₂, and produces a 4-bit output as a basic needle position control code KD given to the calculation device of needle position PVA₁. The NOR circuit NOR₄ directly receives the output P of the memory ROM₂ for the ordinary patterns not accompanied by the pattern memorizing operation. OR circuit OR₄ receives the output OUT of all bits of the memory RAM, and has the output connected to the needle position calculating device PVA₁. In this embodiment, if the pattern selecting switch SW₁ is operated to select the straight stitches, the designation code makes the output OUT of the memory RAM 0 0 0 (the corresponding relation is not shown), and gives 0 to the calculating device PVA₁, and gives a signal including 1 for the patterns other than the straight stitches.

The needle position calculating device PVA₁ receives the needle position control signal DB of the memory ROM₁, the needle position reduction rate signal KB, the basic needle position control code KD and the output signal of the OR circuit OR₄, and makes a calculation (DB-KD)×KB+KD. When the output signal of the OR circuit OR₄ is 1, the calculating device PVA₁ gives the result of the calculation to the stitch forming device DV. When the output signal of the OR circuit OR₄ is 0, the calculating device PVA₁ gives the result of the calculation as the data KD to the stitch forming device DV. The fabric feed calculating device PVA₂ receives the feed control signal DF and the feed reduction rate signal KF, and makes a calculation DF×KF, and gives the result of the calculation to the stitch forming device DV.

With the above-mentioned combination of elements, the operation of the control circuit will now be described in reference to the time charts in FIGS. 3 and 4. If one of the pattern selecting switches SW₁ is operated to select the tulip pattern as shown in FIG. 1, a falling signal is produced to operate the monostable multivibrator circuit MM₁. Then the latch circuit L₁ is operated to latch a new data NEW in place of an old data OLD, and the temporal memory RAM is operated to memorize a new data NEW in place of an old data OLD. At this time, it is to be assumed that the address (ad) of the memory is n-1. As the flip-flop circuit FF₁ is reset with operation of the pattern selecting switch SW₁, the AND circuit AND₆ nullifies the signal of the switch SW₁, and therefore the counter CT is not reset and has no count-up signal.

Subsequently, if the memory switch SW₂ is operated, a falling signal is produced to operate the monostable multi-vibrator circuit MM₂ for producing a pulse signal, and then the delay circuit TD₁ is operated to produce a pulse of the same width as that of the monostable multivibrator circuit MM₂. With the combination of the two pulse signals, the AND circuits AND₁, AND₂, AND₃ produce a pulse one after another as shown in FIG. 4. The mode designation terminal R/W of the memory RAM is made low level with the rising signal of the AND circuit AND₁, and the new data NEW is memorized again at the address (ad), which is n-1, of the memory RAM. With the subsequent rising signal of the AND circuit AND₂, the counter CT starts to count up, and the address (ad) becomes (n). With the subsequent rising signal of the AND circuit AND₃, the latch circuit L₂ latches the output data (n) of the counter CT.

Then if another pattern selecting switch SW₁ is operated to select the zigzag pattern as shown in FIG. 1 in combination with the tulip pattern, the latch circuit L₁ latches the pattern designation signal. Subsequently if the memory switch SW₂ is operated, the memory RAM is ordered, through the AND circuit AND₁, NOR circuit NOR₁, to memorize the pattern designation signal at the address (n) thereof. In the same manner, the counter CT starts to count up, and the address (ad) becomes n+1. With such alternate operations of the switches SW₁, SW₂, the memory RAM is inscribed with the pattern data with advance of the addresses, and the latch circuit L₂ latches the output data of the counter CT as a total number of patterns to be stitched. In this embodiment, it is to be assumed that the tulip and zigzag patterns have been memorized in combination as shown in FIGS. 1(A) and 1(B).

With the aforementioned selection of the tulip pattern, the basic needle position control signal P of the memory ROM₂ is high level, and the flip-flop circuit FF₂ is set with the subsequent operation of the memory switch SW₂ and by way of the AND circuit AND₂, OR circuit OR₁, AND circuit AND₇. With the aforementioned subsequent selection of the zigzag pattern, one input of the AND circuit AND₆ is high level, but the flip-flop circuit FF₂ is not reset because the flip-flop circuit FF₁ is reset. Therefore, after the selection of the first pattern, the basic needle position control code KD of the calculating device PVA₁ remains 0 0 0 0, i.e., decimally 0.

Then if the machine controller (not shown) is operated to close the switch SW₃, the flip-flop circuit FF₁, is set. Then the counter CT is reset, and the address (ad) of the memory RAM becomes 0. This corresponds to the initial address of the stitch control data of the first tulip pattern stored in the memory ROM₁, and is mentioned hereinbefore as the address n-1. The calculating devices PVA₁, PVA₂ respectively receive the needle position control data DB and the feed control data DF read out from the memory ROM₁ at the initial address A₇ -A₅ of the address signal A₇ -A₀ (the rest are all 0) of the tulip pattern, and the corresponding reduction rate data KG, KF respectively of the needle swing adjusting device VRB and the feed adjusting device VRF. The calculating device PVA₁ further receives the basic needle position control code KD as 0 0 0 0 and the signal 1 of the OR circuit OR₄, and makes a calculation (DB-0)×KB+0 and gives the result to the stitch forming device DB.

As the sewing machine is rotated, the pulse generator PG is operated in synchronism with rotation of the drive shaft of sewing machine and produces a timing pulse. The first pulse reads out the data DB, DF from the initial address of the memory ROM₁ for the first stitch, and correspondingly the address data B₄ -B₀ are read out and latched at the timing buffer TB for the address input A₄ -A₀ of the second stitch. Thus the stitches are progressively produced as the sewing machine rotates. As the address data DB, DF are O, which are read out together with the stitch control data DB, DF for the last stitch of the unit pattern, the counter CT counts up. Then the memory RAM designates the initial address of the next zigzag pattern of the memory ROM₁. The stitches are similarly produced, and the counter CT counts up. When the value of the counter comes to be in accord with the total number of patterns latched in the latch circuit L₂, the monostable multivibrator circuit MM₆ is operated to reset the counter. Therefore, the stitch is returned to the first one of the tulip pattern, and the combination of patterns is repeatedly produced. As the basic needle position control code KD and the output of OR circuit OR₄ are constant all through the production of stitch control data DB, DF in formation of the two stitch patterns, the calculations (DB-0)+0=DB is obtained in case the needle swing reduction rate KB by the needle swing adjusting device VRB is 1, and as the result, the maximum (not reduced) combination of patterns is produced as shown in FIG. 1(A). If the reduction rate KB is 0.5, the calculation (DB-0)×0.5=0.5 DB is obtained, and as the result, the combination of patterns is produced as shown in FIG. 1(B) which is 1/2 of the needle swing amplitude with the basic needle position L. With respect to the feed control, the theory is the same with that of the needle position control and therefore the explanation is omitted here.

If the pattern of straight stitches is selected in place of the zigzag stitch pattern to be combined with the tulip pattern, the flip-flop circuit FF₂ is set due to the property of the tulip pattern, and the basic needle position control code KD is 0 0 0 0 and the tulip pattern is produced in the same manner as above-mentioned. Upon subsequent stitching of the straight stitches, the output OUT of the memory RAM is 0 0 0, and the output of the OR circuit OR₄ is 0. The output of the calculating device PVA₁ is 0 0 0 0 which is the data of the basic needle position control data, and the basic needle position is shifted to the position L irrespectively of the stitching process and the adjustment by the adjusting device VRB.

As to the formation of these three patterns individually, the memory switch SW₂ is not operated, and therefore the flip-flop circuit FF₂ is not reset. Since the NOR circuit NOR₄ directly receives the output P of the memory ROM, the basic needle position control signal KD is 0 0 0 0 for the tulip pattern, and 1 1 1 1 for the other patterns. Therefore, the tulip pattern is formed in the manner as aforementioned. As to the zigzag pattern, the output of the calculating device is (DB-15)×KG+15, and the result is DB when the reduction rate KB is 1, and the maximum zigzag pattern is produced as shown in FIG. 1(A). If the reduction rate KB is 0, the result of calculation is 15, and the zigzag pattern is reduced on the center basic needle position M. As to the straight stitches, the basic needle position control signal KD is 1 1 1 1, and the output of the OR circuit OR₄ is 0. The output of the calculating device PVA₁ is therefore 1 1 1 1 which is the same value with the data KD. Thus, the straight stitches are formed on the center basic needle position M. 

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:
 1. An electronic sewing machine comprising: a first memory storing stitch control data for different stitch patterns to be selectively produced, pattern selecting means including a number of pattern selecting switches which are selectively operated to produce a pattern signal designating the corresponding one of the patterns stored in the first memory, pattern memory control means operated to determine a combination of different patterns, a second memory operated in response to the operation of the pattern selecting means and of the pattern memory control means to memorize the combination of different patterns in a predetermined sequence, needle swing adjusting means operated to adjust the swinging amplitude of the needle with a common variation rate with respect to each of the stitch control data read out from the first memory in response to the designation of the pattern signals memorized in the second memory, a third memory storing basic needle position designating signals each specific to the patterns stored in the first memory, basic needle position control means operated in reponse to the operation of the pattern memory control means to memorize a specific one of the basic needle position designating signals of the third memory to control the stitches of the designated combined patterns with a common basic needle position, calculating means operated in response to the output signal of the basic needle control means, the stitch control signal of the first memory and the output signal of the needle swing adjusting means to adjust the swinging amplitude of the needle with a common variation rate with respect to each of the stitches of the combined patterns, and to set a common basic needle position for the patterns, and stitch forming means operated in response to the output of the calculating means to produce the stitches of the combined patterns. 